Non-compliant medical balloon having braided or knitted reinforcement

ABSTRACT

A non-compliant medical balloon comprises a base balloon including a pair of spaced-apart, generally conical end sections and a generally cylindrical center section connected therebetween. A braided fabric sleeve surrounds at least a portion of the base balloon, wherein the sleeve is formed of at least three substantially inelastic fibers intertwined in such a way that no two of the three fibers are twisted exclusively around one another. The sleeve is permanently affixed to the outer surface of the base balloon so as to prevent excessive expansion of the base balloon when the base balloon is internally pressurized.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/690,735, which is a continuation-in-part of U.S. application Ser. No.10/967,038, filed Oct. 15, 2004, and entitled MEDICAL BALLOON HAVINGSTRENGTHENING RODS; a continuation-in-part of U.S. application Ser. No.10/967,065, filed Oct. 15, 2004, and entitled NON-COMPLIANT MEDICALBALLOON HAVING AN INTEGRAL NON-WOVEN FABRIC LAYER; and acontinuation-in-part of U.S. application Ser. No. 10/966,970, filed Oct.15, 2004, and entitled NON-COMPLIANT MEDICAL BALLOON HAVING AN INTEGRALWOVEN FABRIC LAYER, the disclosures of which are incorporated herein byreference for all purposes. This application also claims the benefit ofU.S. Provisional Application for Patent Ser. No. 60/785,864, filed Mar.24, 2006, and entitled NON-COMPLIANT MEDICAL BALLOON HAVING BRAIDEDREINFORCEMENT

TECHNICAL FIELD

The following disclosure relates to medical balloons, and moreparticularly to non-compliant medical balloons used with a ballooncatheter in medical procedures such as angioplasty.

BACKGROUND

Medical balloons have been widely used in medical procedures. Typically,an uninflated medical balloon is inserted into a body-space, e.g., bloodvessel, urological vessel, etc. by means of a catheter. Afterpositioning at the desired location within the body, the medical balloonis inflated by introducing a fluid into the balloon through the catheterunder pressure. The inflation fluid causes the volume of the medicalballoon to expand, and the adjacent body-space is similarly expanded. Inprocedures such as angioplasty, the inflated medical balloon may be usedto open a collapsed or blocked artery. The fluid may then be withdrawnfrom the balloon, causing it to collapse to facilitate its removal fromthe body.

It is known to use medical balloons made of non-compliant materials forprocedures where the dimensions of the inflated medical balloon must beuniform and predictable, even when different inflation pressures areused. Because the maximum diameter of such non-compliant balloons ispredetermined, they are less likely to rupture or dissect the vessel orbody-space when the balloon expands.

Before inflation, non-compliant medical balloons are typically foldedtightly against the catheter in order to reduce the assembly's overallcross-section (i.e., to better fit through small body-spaces). It isthus normally desirable that the walls of the balloon be as thin aspossible, so that the uninflated balloon will have the smallest diameterpossible. However, medical balloons are increasingly being used to openbody spaces restricted by tough tissues such as strictures, scarring orcalcified areas. Stretching such tough tissue often requires the medicalballoon to exert significant pressure. It is thus desirable that amedical balloon be capable of withstanding high pressure withoutrupturing. The pressure at which the walls of the balloon are expectedto rupture is termed the “burst strength.”

In the pursuit of non-compliant medical balloons having both thin wallsand high burst strength, it is known to make so-called “composite”balloons from a blow-molded thin film polymeric material havingexternally applied fiber-reinforcements. In some cases, such reinforcingfibers may be “filament wound” around the blow-molded “base” balloon ina simple helical fashion. In other cases, successive layers of fibersmay be laid over the base balloon in adjacent, but separate (i.e., notwoven together) layers having different orientations. While suchfiber-reinforced balloons have resulted in improved performance comparedto non-reinforced balloons, further improvement is desired. Anon-compliant medical balloon having an integral non-woven fabric layeris disclosed in co-pending U.S. patent application Ser. No. 10/967,065entitled “Non-Compliant Medical Balloon Having an Integral Non-WovenFabric Layer,” filed Oct. 15, 2004, the disclosure of which isincorporated herein by reference for all purposes. A non-compliantmedical balloon having an integral woven fabric layer is disclosed inco-pending U.S. patent application Ser. No. 10/966,970 entitled“Non-Compliant Medical Balloon Having an Integral Woven Fabric Layer,”filed Oct. 15, 2004, the disclosure of which is incorporated herein byreference for all purposes. A medical balloon having strengthening rodsis disclosed in co-pending U.S. patent application Ser. No. 10/967,038entitled “Medical Balloon having Strengthening Rods,” filed Oct. 15,2004, the disclosure of which is incorporated herein by reference forall purposes.

“Braiding” refers to a system of fiber architecture in which three ormore fibers are intertwined in such a way that no two fibers are twistedexclusively around one another. Braiding can be used to form fabricstructures such as sheets, tapes, and even tubular sleeves having acontinuous annular wall with a passage down the middle. The braidedarchitecture resembles a hybrid of filament winding and weaving: As infilament winding, a tubular braid features seamless fiber continuityfrom end to end of a part; braided fibers are mechanically interlockedwith one another. The resulting braid exhibits unique propertiesallowing it to be highly efficient in distributing loads. Specifically,because all the fibers within a braided structure are continuous andmechanically locked, a braid has a natural mechanism thatevenly-distributes load throughout the structure.

“Knitting” refers to a system of fiber architecture produced byintertwining threads in a series of interconnected loops rather than byweaving. In this fashion, the loops of fibers are mechanicallyinterlocked. A weft-knitted structure consists of horizontal, parallelcourses of fibers and requires only a single fiber. Alternatively, warpknitting requires one fiber for every stitch in the course, orhorizontal row; these fibers make vertical parallel wales. Circularknitting refers to construction of a seamless tube whereas flat knittingis used to construct a flat structure.

The use of braided reinforcements for compliant medical balloons hasbeen suggested. U.S. Pat. No. 5,647,848 to Jorgensen discloses acompliant medical balloon including an elastomeric balloon and areinforcing structure that may include braided fibers. However, in suchcompliant balloons, the braid length and/or braid angle of the braidedfiber structure changes between the deflated and inflated states, acondition that may be undesirable for non-compliant balloons.

A need therefore exists for a non-compliant medical balloon havingbraided fiber reinforcement. Preferably, the non-compliant braided fiberreinforced balloon will have a braid angle that does not changesignificantly between the deflated and inflated states.

A need further exists for a non-complaint medical balloon having knittedfiber reinforcement. Preferably, the non-compliant knitted fiberreinforced balloon will have knitted fibers that do not significantlychange position relative to the surface of the base balloon between thedeflated and inflated state.

SUMMARY

In one aspect thereof, a non-compliant medical balloon includes a baseballoon having a pair of spaced-apart, generally conical end sectionsand a generally cylindrical center section connected therebetween. Abraided fabric sleeve surrounds at least a portion of the base balloon,wherein the portion has at least two different diameters, and whereinthe sleeve is formed of at least three substantially inelastic fibersintertwined in such a way that no two of the three fibers are twistedexclusively around one another. The sleeve is permanently affixed to theouter surface of the base balloon so as to prevent excessive expansionof the base balloon when the base balloon is internally pressurized.

In one configuration, a non-compliant medical balloon includes a baseballoon including a generally cylindrical center section with first andsecond generally conical end portions extending from the center portionand having shoulders at the junctures of the conical end portions andthe cylindrical center section. First and second reduced diameter necksextend from the apex of each of the conical end portions. A fabricsleeve is disposed over the base balloon, the sleeve being formed frommechanically interlocked, substantially inelastic fibers. The fibers aremechanically interconnected at spaced apart junctions where a fiberpasses over an interconnecting fiber and changes direction untilreaching the next junction. The sleeve extends continuously over thefirst conical end portion, the generally cylindrical center portion andthe second conical end portion.

The fabric sleeve may be formed as a separate freestanding article thatis subsequently pulled over the base balloon. Alternatively, the fabricsleeve may be formed in-situ over the base balloon. In one variation,the sleeve is formed from substantially inelastic ribbon-shaped fiberseach having a width greater than thickness.

In one aspect, the sleeve of non-compliant medical balloon is braidedfrom at least three substantially inelastic fibers intertwined so thatno two of the three fibers are twisted exclusively around one another.In another, the fabric sleeve comprises a seamless tube extendingcontinuously over the base balloon from the first neck to the secondneck. Each fiber may be secured to the base balloon along substantiallythe entire length of the fiber to the base balloon.

In another aspect, the non-compliant medical balloon further includes anouter layer wherein the fabric sleeve is positioned between the baseballoon and the outer layer and wherein the outer layer is secured tothe base balloon with an adhesive or, alternatively, fused to the baseballoon, such that the position of the fibers relative to the surface ofbase balloon does not substantially change when the balloon is inflated.In one aspect, a higher-strength adhesive is used to affix thereinforcing fibers to the base balloon at the conical end sections whilea lower strength adhesive is used to secure the fibers to the remainderof the base balloon.

In another variation, the fabric sleeve is formed from substantiallyinelastic fibers that extend in a substantially longitudinal directionbetween the necks while changing directions at spaced apart intervalswith substantially no fibers extending completely around thecircumference of the base balloon. Alternatively, the fabric sleeve isformed from substantially inelastic fibers that extend in asubstantially circumferential direction around the base balloon whilechanging directions at spaced apart intervals with substantially nofibers extending continuously between the necks in a longitudinaldirection.

In another aspect, at least some of the mechanically interlocked,substantially inelastic fibers extend over the shoulders of the baseballoon at an angle relative to the longitudinal axis of the cylindricalcenter portion and at an angle relative to a plane intersecting a circledefined by each shoulder such that transverse and longitudinalcomponents of forces applied to the base balloon are transmitted acrossthe shoulders.

In another aspect, a method of making a non-compliant medical balloonincludes forming a base balloon having a generally cylindrical centersection with first and second generally conical end portions extendingfrom the center portion and with shoulders at the junctures of theconical end portions and the cylindrical center section. First andsecond reduced diameter necks are formed extending from the apex of eachof the conical end portions. A fabric sleeve is formed from mechanicallyinterlocked, substantially inelastic fibers, the fibers beingmechanically interconnected at spaced apart junctions where a fiberpasses over an interconnecting fiber and then changes direction suchthat the fiber intersects the junction at a first angle and extends awayfrom the junction at a second angle. The fabric sleeve is positionedover the base balloon such that the fabric sleeve conforms to thesurface of the base balloon and extends continuously over the baseballoon between the first and second necks. The fabric sleeve is securedto the base balloon such that an angle between a longitudinal axis ofthe base balloon and fibers extending over the shoulders of the balloondoes not change when the balloon is inflated or collapsed. In onevariation, an overcoat is formed over the fabric sleeve such that thefabric sleeve is secured between the overcoat and the base balloon. Inanother, fabric sleeve is formed in-situ over the base balloon. Thefabric sleeve may be one of knitted and braided construction.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding, reference is now made to thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a partial cross-sectional side view of a medical balloon inaccordance with the PRIOR ART;

FIG. 2 is an enlarged cross-sectional view of the side junction regionof the PRIOR ART medical balloon of FIGURE 1:

FIG. 3a is a partial cross-sectional side view of a non-compliantmedical balloon having braided fiber reinforcement in accordance withone embodiment of the disclosure;

FIG. 3b is a side view of a mandrel suitable for use in forming a basecomponent of the medical balloon of FIG. 3.

FIG. 4a is an enlarged portion of the medical balloon of FIG. 3;

FIG. 4b is an enlarged portion of another medical balloon having analternative braid variation;

FIG. 4c is an enlarged portion of yet another medical balloon having afurther alternative braid variation;

FIG. 4d is a cross-sectional end view of a fiber bundle used in the FIG.4 b;

FIG. 4e is a cross-sectional end view of an alternative fiber bundle;

FIGS. 5a-5d show a method of making a non-compliant medical balloonhaving a braided fiber reinforcement layer in accordance with anotherembodiment;

FIG. 5e is a partial sectional view of the medical balloon taken alongline e-e of FIG. 5 d;

FIG. 5f is a partial sectional view illustrating an alternateconstruction of the medical balloon of FIG. 5 d;

FIG. 6 shows a method of making a non-compliant medical balloon having abraided fiber reinforcement layer in accordance with yet anotherembodiment;

FIG. 7a is a side view of a non-compliant braid-reinforced medicalballoon having a further over-coating layer;

FIG. 7b is a perspective view of the non-compliant braid reinforcedballoon of FIG. 7 in the collapsed or deflated state;

FIG. 8 shows a non-compliant braid-reinforced medical balloon havingdifferent strength adhesives used at different portions of the balloon;

FIG. 9a is a partial cross-sectional side view of a non-compliantmedical balloon having knitted fiber reinforcement in accordance withone embodiment of the disclosure;

FIG. 9b is an end view of the non-compliant medical balloon of FIG. 9;

FIG. 10 is an enlarged portion of the medical balloon of FIG. 9;

FIG. 11 is a partial sectional view of the medical balloon of FIG. 9taken along line 11-11 of FIGS. 10; and

FIG. 12 is a partial sectional view of an alternate construction of themedical balloon of FIG. 10.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numbers are usedherein to designate like elements throughout the various views,embodiments of the non-compliant medical balloon are illustrated anddescribed, and other possible embodiments are described. The figures arenot necessarily drawn to scale, and in some instances the drawings havebeen exaggerated and/or simplified in places for illustrative purposesonly. One of ordinary skill in the art will appreciate the many possibleapplications and variations based on the following examples of possibleembodiments.

Referring now to FIG. 1, there is illustrated a non-compliant medicalballoon in accordance with the prior art, in its inflated configuration.The medical balloon 100 includes a base balloon 102 having pairs ofconical end sections 104 and a relatively cylindrical center-section 106located therebetween. A small-diameter cylindrical neck 108 typicallyextends outwardly from each end section 106. For use, the balloon 100 istypically attached to a catheter 109 (shown in phantom) via the necksection 108. The base balloon 102 is commonly formed using ablow-molding process, resulting in the wall thickness of the endsections tapering considerably from the relatively thick neck 108 to therelatively thin center section 106. Fiber reinforcements may be appliedto the outer surface of the base balloon 102, including a first layer oflongitudinal fibers 110 oriented generally along the longitudinal axisof the balloon and a second layer of hoop fibers 112 oriented generallyperpendicular to the longitudinal fibers, i.e., circumferentially aroundthe axis of the balloon. It will be understood that the reinforcingfibers 110 and 112 are typically attached to the base balloon 102 usingan adhesive material.

Referring now to FIG. 2, there is illustrated an enlarged portion of theprior art balloon of FIG. 1, showing the balloon wall at the junctionbetween the conical end section 104 and the center section 106. Forpurposes of illustration, the balloon in FIG. 2 is shown in crosssection with the reinforcing fibers 110 and 112 (which are attached tothe outer surface of the base balloon) visible through the transparentrear surface of base balloon 102. A recurring problem with such priorart balloons is failure of the adhesive bond on the sloped end sections104, which allows the hoop fibers 112 on the end sections 104 to moveduring inflation, e.g., from their original position 112′ (indicated inbroken line) to a new position 112″ further down the conical slope (asindicated by the small arrows). Once the hoop fibers 112 move out ofposition, the (now un-reinforced) corner section of the base balloon 102may bulge out from its original position 114′ (indicated in broken line)to a distended position 114″and fail due to pressure-induced strain(i.e., thinning). Such failures may include rupture of the balloon andrelease of pressurized inflation fluid into the patient.

Referring now to FIG. 3a , there is illustrated a non-compliant medicalballoon 300 having a braided fiber reinforcement layer in accordancewith the disclosure. As in the prior art balloon 100 of FIG. 1, themedical balloon 300 may include a base balloon or balloon base layer 302having a pair of conical end sections 304 and a relatively cylindricalcenter-section 306 located therebetween. A small-diameter cylindricalneck 308 may extend outwardly from each end section 306 for attachmentto a catheter 309 (shown in phantom). The base balloon 302 may be formedof a thin film polymer material using a blow-molding process, resultingin the wall thickness of the end sections tapering considerably fromrelatively thick at the neck 308 to relatively thin at the centersection 306. As in the prior art, fiber reinforcements are applied tothe outer surface of the base balloon 302, however, in this embodiment,the fiber reinforcement layer comprises at least one single layer 310 ofbraided fibers 312 which are attached to the base balloon 302 when inits inflated configuration. The braided fiber reinforcement layer 310may include three or more fibers 312 intertwined in such a way that notwo fibers are twisted exclusively around one another. Braided fiberreinforcement layer 310 may comprise a seamless tube or may beconstructed from a braided reinforcement fabric having one or moreseams.

In some embodiments, the braided fiber reinforcement layer may be theonly reinforcement layer. In other embodiments, additional fiberreinforcement layers of conventional longitudinal or circumferentialconfiguration may be used in addition to the braided fiber layer. Theseconventional layers may be affixed to the balloon before and/or afterthe braided fiber layer.

For purposes of illustration, the braid form shown on the braided fiberreinforcement layer 310 of FIG. 3a has a very high “porosity,” i.e., arelatively large amount of open space between braid fibers 312. It willbe appreciated, however, that other braid forms having differentpatterns and porosities (including those having adjacent fibers withessentially no porosity) may be used in other embodiments. It will alsobe appreciated that different braid architectures may be used for thebraided fiber reinforcement layer 310, including biaxial, triaxial andtailored braid forms.

In one embodiment, braided fiber reinforcement layer 310 has a braiddensity of from about 20 to about 60 pics per inch. In a preferredembodiment, braided fiber reinforcement layer 310 has a braid densityfrom about 30 to about 50 pics per inch. In another variation, braidedreinforcement layer 310 is formed with a braid density of about 45 toabout 50 pics per inch.

The diameter d′ of an inflated fiber-reinforced medical balloon 300 inaccordance with the one embodiment may be about ten millimeters. Inother variations, balloons 300 may have a diameter d′ of about threemillimeters to about thirty millimeters. The working length l′ of aninflated fiber-reinforced medical balloon 300 in accordance with oneembodiment may be about eight centimeters. In other variations, theworking length 1′ of balloons 300 may vary from about one and one-halfcentimeters to about 15 centimeters. In various embodiments, theinclination angle of the conical end portion 304 of balloon 300 may varyfrom about twelve degrees to about twenty degrees. It will be recognizedby those having skill in the art that the fiber-reinforced balloon 300could be made in a wide variety of diameters d′ and lengths l′ and witha variety of inclinations at the conical end portions 304 of theballoon.

Fiber-reinforced balloon 300 is generally suitable for use as a medicalballoon. Medical balloons are commonly used in angioplasty, orthopaedicsand other medical procedures where it is necessary to create a spacewithin the body. It may be recognized by those skilled in the art thatthe qualities of a fiber-reinforced balloon 300 may make the balloon 300suitable for other uses. The fiber-reinforced balloons 300 may be usednon-medically to create space or otherwise. The fiber-reinforcedballoons 300 may be used in ways beyond the present uses of medicalballoons.

The base layer balloon 302 is typically formed of a thin film polymericmaterial, or other suitable materials with high strength relative tofilm thickness. Polymers and copolymers that can be used for the baseballoon 302 include the conventional polymers and copolymers used inmedical balloon construction, such as, but not limited to, polyethylene,PET, polycaprolactam, polyesters, polyethers, polyamides, polyurethanes,polyimides, ABS, nylons, copolymers, polyester/polyether blockcopolymers, ionomer resins, liquid crystal polymers, and rigid rodpolymers. The base layer balloon 302 may typically be formed as ablow-molded balloon of highly oriented polyethylene terephthalate (PET).

The strength of fiber-reinforced balloons 300 permits the use of baselayer balloons 302 having a wall thickness less than conventional orprior art balloons without sacrifice of burst strength, abrasionresistance, or puncture resistance. The wall thickness of base layerballoon 302 may be in the range of about 0.0005 inch to about 0.002inch. In accordance with the disclosed embodiment, the base layerballoon 302 may have a wall thickness of 0.0008 inch. It will berecognized by those skilled in the art that the wall thickness of thebase layer balloon 302 may be increased or diminished as required.

The balloon base layer 302 may be omitted from a fiber-reinforcedballoon 300, in accordance with one embodiment. Instead, a base layer302 of a polymer may be applied to a removable mandrel 320 (FIG. 3b )and cured into the shape of a balloon. The mandrel 320 may be made froma variety of materials in the shape of the interior wall of the desiredfinished balloon. For example, a removable base balloon may be used asthe mandrel 320. The mandrel 320 may be made of collapsible metal orpolymeric bladder, foams, waxes, low-melting metal alloys, and the like.After the polymer is cured, the base layer 302 may be removed frommandrel 320 or the mandrel removed from the base layer by melting,dissolving, fracturing, compressing, pressurizing, or other suitableremoval techniques.

Forming balloon 300 using mandrel 320 permits the use of alternativeprocessing techniques can be employed which do not limit the parametersof temperature, force, and pressure, during the forming process. Thematerials used for the balloon construction are not limited to thosethat conform to the present art of forming a balloon with pressure,temperature, and force, such as, for example, those utilized for forminga balloon from a tube made from a polymeric material. Strongerfiber-reinforced balloons 300, with higher pressure and better damageresistance, can be formed with smaller geometries, in particularballoons having thinner walls. The resulting fiber-reinforced balloons300 may be stronger, softer and more flexible.

Referring now to FIG. 4a , there is illustrated an enlarged portion ofthe medical balloon 300 showing how the individual fibers 312 may belaid over the surface of the base balloon 302 to make up the singlebraided fiber reinforcement layer 310. The fibers 312 are preferablyformed of a substantially inelastic material. After placement on theballoon, each fiber 312 leading into, and out of, a junction orintersection 314 with other fibers will form an angle (denoted “A”) withthe longitudinal axis 316 of the balloon. The braided fiber layer 310 isaffixed to the outer surface of the base balloon 302 using an adhesive(not shown). In some embodiments, the braid angle “A” may vary fromlocation to location over the surface of the balloon to provide the bestfit for the braided layer. In preferred embodiments, however, the braidangle “A” at each particular location does not substantially change whenthe balloon goes from an uninflated state to an inflated state, or viceversa.

Depending upon the braiding pattern and style used, the fibers in thebraided layer may be looped around each other one or more times at eachintersection, or they may merely pass above or below one another at eachintersection. Regardless, the fibers will form an angle with one anotherat each intersection.

In one variation, a single fiber 312 may extend continuously over thelength of base balloon 302 between necks 308. In this variation, thefiber 312 changes direction at longitudinally spaced apart intervalscorresponding to junctions 314 with interconnecting fibers while stillextending continuously in a generally longitudinal direction over baseballoon 302 between necks 308. Fiber 312 changes direction in that theinterior angle (designated “I”) between the fiber approaching thejunction and the fiber extending away from the junction is less than onehundred and eighty degrees in the plane defined by the fiber. In thisconfiguration, fibers 312 may extend longitudinally over base balloon302 between necks 308 with substantially no fibers extendingcontinuously completely around the circumference of the base balloon.

In another variation, a single fiber 312 may extend continuously aroundthe circumference of base balloon 302. In this configuration, the fiber312 changes direction at circumferentially spaced apart intervalscorresponding to junctions 314 with interconnecting fibers while stillextending in a generally circumferential direction around thecircumference of base balloon 302. In the case of a substantiallyrectangular braid, the change in direction is approximately ninetydegrees. In this variation, fibers 312 may extend continuously andcircumferentially around base balloon 302 between necks 308 with nofibers extending continuously over the length of base balloon 302between necks 308.

The fibers 312 of fiber layer 310 may be inelastic fiber, typically madeof an inelastic fibrous material. An inelastic fiber is a fiber that hasvery minimal elasticity or stretch over a given range of balloonpressures. Some fibrous materials are generally classified as inelasticalthough the fibrous material may have a detectable, but minimal,elasticity or stretch at a given balloon pressure.

The fibers 312 of braided fiber layer 310 may be high-strength fibers,typically made of a high-strength fibrous material. Some high strengthinelastic fibrous materials may include Kevlar, Vectran, Spectra,Dacron, Dyneema, Teflon (PBT), Zylon (PBO), Polyimide (PIM), other ultrahigh molecular weight polyethylene, arm-aids, polyesters nylons, and thelike.

In one variation, fibers 312 are ribbon-shaped, where the width of theindividual fiber is larger than the thickness of the fiber such that thefiber has a somewhat rectangular cross-section. Fibers 312 have anominal thickness of about 0.003 inch and may be flattened on a rollmill or otherwise processed to achieve the ribbon shape. The dimensionsof the flattened fibers may vary from about 0.0005 inch to about 0.003inch or more, depending upon the particular material and application.

Referring now to FIGS. 4b and 4c , in other variations, the braidedreinforcing layer is formed by first forming three or more tows, i.e.,untwisted bundles of smaller continuous fibers or filaments, and thenbraiding the tows together. FIG. 4b shows a portion of a reinforcinglayer 410 braided in an “over-1-under-1” diamond bi-axial pattern, andFIG. 4c shows a portion of another reinforcing layer 420 braided in an“over-2-under-2” regular bi-axial pattern. In the diamond braid patternof FIG. 4b , a first plurality of tows or bundles of filaments 412extend in a first direction, while a second plurality of tows 414 extendin a second direction. Each tow 412 travels over and under a single tow414 at a time, while each tow 414 similarly travels over and under asingle tow 412 at a time to form the diamond braid pattern. In FIG. 4c ,two pluralities of tows are again used, a first plurality of tows 422extending in a first direction, and a second plurality of tows 424extending in a second direction. In this case, however, each tow 422travels over and under two tows 424 at a time, while each tow 424similarly travels over and under two tows 422 at a time to form thebraid pattern. These examples are intended to be illustrative ratherthan limiting, as it will be appreciated that any other regular or fancybi-axial or tri-axial braid pattern or other braid pattern known in theart can be used to form the braided reinforcing layer.

Regardless of the braiding pattern used for the braided reinforcementlayer, each course, or row of fibers (or tows) will define a braid angle(denoted A1 and A2) with the longitudinal axis 316 of the balloon, andeach intersection between fibers (or tows) will define an intersectionangle (denoted B). Once the braided fiber reinforcement layer has beenaffixed in place on the balloon, these angles will remain substantiallyunchanged when the balloon goes from an uninflated state to an inflatedstate.

Referring now to FIGS. 4d and 4e , the fiber bundles or tows used in thebraided reinforcing layers such as those shown in FIGS. 4b and 4c mayhave different cross sections. FIG. 4d shows a tow 430 comprising aplurality of individual fibers 432 bundled such that the tow has agenerally circular cross-section, wherein the thickness (denoted t) ofthe tow is substantially the same as the width (denoted w). FIG. 4eshows another tow 440 comprising a plurality of fibers individual 442bundled such that the tow has a generally flat or ribbon-likecross-section, wherein the thickness t of the tow is substantiallysmaller than the width w. It will be appreciated that in some cases allof the fibers in a particular tow may be the same size (e.g., diameter),same strength, and the same material, whereas in other cases fibers ofdifferent sizes, strengths and/or materials may be used in the same tow.Further, the braided reinforcing layer may be formed by braiding uniformtows, or by braiding tows having different characteristics.

Referring now to FIGS. 5a-5f and 6, braided fiber reinforcement layer310 may be applied to base balloon 302 using several methods. In onemethod, a free-standing braided fiber sleeve 510 formed from fibers 512is prepared independently of the base balloon 502 (FIG. 5a ). Thebraided sleeve 510 may be a seamless biaxial or triaxial tubular sleeve.Preferably, the sleeve 510 will have seamless fiber continuity from endto end. In one variation, each of fibers 512 extends continuously overbase balloon 502 from end to end. Subsequently, the braided fiber sleeve510 is pulled over the inflated balloon 502, expanding over the contoursof the balloon (FIG. 54 Base balloon 502 may be formed or positioned ona mandrel, similar to that illustrated in FIG. 3a prior to pullingbraided fiber sleeve 510 over the base balloon 502.

Finally, the sleeve 510 is snugged down against the base balloon 502using the “Chinese finger trap” effect to conform the sleeve to thedimensions of the base balloon and the excess sleeve material 520 isthen cut off and discarded (FIG. 5c ). The braided reinforcement 510 istypically impregnated with resin or adhesive such as a polyurethaneafter positioning, although in some embodiments, the fiber sleeve isimpregnated prior to placement. The resin or adhesive coated fibers areconsolidated with the base balloon 502 by curing to form the finishednon-compliant braid-reinforced balloon 500. In the embodiment justdescribed, the braided fabric layer 510 is the only reinforcing layer,but in other embodiments, the braided fabric layer may be used above,below, or between other reinforcing layers.

In another method (FIG. 6), the braided fiber reinforcement layer 610 isbraided directly onto the base inflated balloon 602 using braidingequipment of known design. In this in situ method, the adhesive may beapplied to base balloon 602 and/or to the reinforcing fibers prior to,during, or after the braiding process. By applying the fibers in situ,the greatest control may be obtained over the fiber density and angle ateach part of the base balloon profile.

Referring to FIG. 5d , a polymer outer coating layer 514 may be appliedover fiber reinforcement sleeve 510 as a film or by means of spraycoating, dipping or other deposition process. The thickness of thepolymeric outer coating layer 514 may be determined by thecharacteristics of the desired fiber-reinforced balloon 500. Thepolymeric solution used for the outer coating layer 514 may be formedfrom the same polymer as the polymer base balloon layer 502. The outercoating layer 514 may be made from a different polymer than the inflatedpolymeric balloon base layer 502. Where the polymers are different, thepolymers may be chosen to be compatible to reduce or prevent separationof the composite balloon 500. As illustrated in FIG. 5e , outer layer514 may be secured to base balloon 502 with an adhesive 516 with fibers514 disposed between the outer layer and the base balloon. In oneembodiment, adhesive 516 secures each fiber 512 substantially entirelyalong its length to base balloon 502 and/or to outer layer 514.Alternatively, as shown in FIG. 5f , outer layer 514 may be fused tobase balloon 520 by means of solvent welding, heat, pressure or acombination thereof. In either case, fibers 514 are secured in positionbetween the base balloon 502 and outer layer 514 such that the braidangle “A” (FIG. 3a ) does not substantially change when the balloon goesfrom an uninflated state to an inflated state.

Polymers and copolymers that may be used as the outer coating layer 514of the fiber/polymeric matrix include the conventional polymers andcopolymers used in medical balloon construction. Typical suitablesubstances may include polyethylene, nylons, polyethylene terephthalate(PET), polycaprolactam, polyesters, polyethers, polyamides,polyurethanes, polyimides, ABS copolymers, polyester/polyether blockcopolymers, ionomer resins, liquid crystal polymers, and rigid rodpolymers.

In one variation, the same or compatible polymer materials polymermaterials are used to form base balloon 502 and outer coating layer 514.As illustrated in FIG. 5f , in this embodiment, rather than using aresin or adhesive to affix fiber layer 510 to base balloon 502, the baseballoon and outer layer 514 are fused together by means of solventwelding, heat, pressure or a combination thereof. Welding base balloon502 to outer coating layer 514 is believed to form a stronger connectionbetween the base balloon and the outer coating. In one variation, fusingbase balloon 502 to outer layer 514 secures each of fibers 512substantially entirely along its length between the base balloon 502 andouter layer 514.

Referring now to FIG. 7a , there is illustrated a non-compliant medicalballoon 700 having braided fiber reinforcement 710 in accordance withanother embodiment. Balloon 700 includes base balloon 702 having conicalend portions 704 connected to a cylindrical center section 706 withreduced diameter necks 708 extending from the apex of each conical endportion 704. In this embodiment, a further over-coating layer 716,formed of a polyether block amide sold under the trademark Pebax® orsimilar thermoplastic material, may be pressure-molded over the braidedfiber reinforcement layer 710 to further hold it in place or to providean abrasion resistant coating to the balloon.

FIG. 7b shows the non-compliant medical balloon 700 in the deflated orcollapsed state. Folds 720 in outer surface 722 decrease the diameter ofthe medical balloon 700 for insertion by means of a catheter or similardevice. The “leaves” of each fold may then be rolled circumferentiallyabout the interior catheter (not shown) within the balloon to form acompact package. As the deflated medical balloon 700 inflates, theballoon folds 720 substantially disappear until the balloon reaches aninflated size as shown in FIG. 7a . Since medical balloon 700 isnon-compliant, once the balloon is fully inflated, it has a length anddiameter that do not change as the pressure on the interior of theballoon increases.

Regardless of the method for applying and affixing the braided fiberreinforcing fibers to the base balloon, after the fibers are adhesivelyaffixed in place, then the angle and location of the braids will notchange between the inflated state and the deflated state of the balloon.Thus, following manufacture, the now composite reinforced balloon may befolded up and rolled to form a small cross-section as with the priorart. When later re-inflated in the body, the braided fiber reinforcingwill maintain its position and spacing along the conical ends and centersections of the balloon to prevent pressure-related failures. If theballoon has been subsequently coated with Pebax®, or anotherover-coating material, then the balloon will also exhibit superiorabrasion-resistant qualities as well.

Referring now to FIG. 8, in yet another embodiment, different strengthadhesives are used at different portions of the balloon 800 to affix thebraided fiber reinforcing layer 810 to the base balloon 802. It will beappreciated that, in most cases, the higher the strength of an adhesive,the lower its flexibility. Since a major location of failures in medicalballoons occurs in the conical end sections 804, in this embodiment, ahigh-strength adhesive (denoted by shaded area “H”) is used to affix thereinforcing fibers 810 to the base balloon 802 at these conical endsections. This prevents the fibers 810 from moving during inflation andcausing a weak point in the balloon. The remaining generally cylindricalcenter section 806 of the balloon may have the fibers 810 adhered usingordinary strength adhesives having improved flexibility. For example, ahigh viscosity urethane adhesive may be used to secure fiberreinforcement layer 810 to conical end section 804 while a lowerviscosity urethane adhesive may be used to secure layer 810 tocylindrical center section 806. Thus, the non-compliant balloon 800exhibits increased burst strength with a minimum reduction in theoverall flexibility of the device.

Referring now to FIGS. 9a, 9b , and 10, a non-compliant medical balloon900 having a knitted fiber reinforcement layer 910 may include a baseballoon 902 having pairs of conical end sections 904 and a relativelycylindrical center section 906 located therebetween. A shoulder 916 isformed at the junctures of each of conical end sections 904 andcylindrical center section 906. Shoulders 916 each define a circle 918circumscribing the perimeter of the juncture of cylindrical centersection 906 and conical end sections 904.

A small-diameter cylindrical neck 908 may extend outwardly from each endsection 904 for attachment to a catheter 909 (shown in phantom). Thebase balloon 902 may be formed of a thin film polymer material using ablow-molding process, resulting in the wall thickness of the endsections tapering considerably from relatively thick at the neck 908 torelatively thin at the center section 906.

In the illustrated embodiment, the fiber reinforcement comprises asingle layer 910 of knitted fibers 912 that is attached to the baseballoon 902 when in its inflated configuration. The knitted fiberreinforcement layer 910 may include rows of loops 914, each of which ispulled through the loops of the row below it. In this manner fibers 912are mechanically interlocked by passing over or under an interconnectedfiber at junctions 924. In one variation, fibers 912 change directionsat each junction 924, while still extending in a generally longitudinalor circumferential direction.

In one variation, knitted fiber reinforcement layer 910 may comprise aseamless tube and in other variations, it may be constructed from a flatknitted reinforcement fabric having one or more seams. In oneembodiment, layer 910 comprises a seamless tube extending continuouslyfrom end-to-end of base balloon 902. In one variation, each of fibers912 extend across shoulder 916 at an angle of less than ninety degreesrelative to longitudinal central axis 920 of base balloon 902 and at anangle relative to the plane defined by circle 918 such that longitudinaland transverse components of forces applied to base balloon 902 uponinflation are transmitted across shoulder 916 by fibers 912.

As illustrated, the knitted fiber reinforcement layer 910 has a veryhigh “porosity,” i.e., a relatively large amount of open space betweenbraid fibers 912. It will be appreciated, however, that other knit formshaving different patterns and porosities may be used in otherembodiments. It will also be appreciated that different knitconfigurations may be used for the knitted fiber reinforcement layer910, including weft, warp, circular, flat and custom knit forms. Theknit density of fiber reinforcement layer 910 will be similar to thebraid density of braided fiber reinforcement layer 310 in FIG. 3 a.

Non-compliant medical balloon 900 including base balloon 902 and knittedfiber layer 910 may be constructed of the same materials in generallythe same manner as balloon 300 of FIG. 3a , except that fiberreinforcement layer 910 is knitted instead of braided. Knitted fiberlayer 910 may be installed on base balloon 902 in substantially the samefashion as described in connection with FIGS. 5A-5C above or,alternatively, knitted in place on base balloon 902. The knitted fabricreinforcing layer may be the only reinforcing layer, or it may beaffixed above, below, or between other reinforcing layers.

Base balloon 902 may be formed from a variety of polymers andcopolymers. For example base balloon 902 may be formed from polyethyleneterephthalate, (PET), polycaprolactam, polyesters, polyethers,polyamides, polyurethanes, polyimides, ABS, nylons, copolymers,polyester/polyether block copolymers, ionomer resins, liquid crystalpolymers, rigid rod polymers and other polymers used for medicalballoons. In one embodiment, base layer balloon 902 be blow-moldedballoon from oriented polyethylene terephthalate (PET). Base balloon 902may also be formed by applying a polymer solution to a mandrel such asillustrated in FIG. 3b and curing the solution.

Turning to FIGS. 10-12, an enlarged portion of the medical balloon 900illustrates the general configuration of individual fibers 912 as laidover the surface of the base balloon 902 to form knitted fiberreinforcement layer 910. In one configuration, knitted fiberreinforcement layer is 910 stretched taut, e.g., to the point thatfurther force will not extend the layer, before the layer is secured tobase balloon 902. Fibers 912 are preferably formed of a high-strengthsubstantially inelastic material. Such fibers may include Kevlar,Vectran, Spectra, Dacron, Dyneema, Teflon (PBT), Zylon (PBO), Polyimide(PIM), other ultra high molecular weight polyethylene, aramids,polyesters nylons, and similar materials. When secured on base balloon902, each loop 914 will have a loop length (denoted “LD”). In oneembodiment, the loop lengths LD of loops 914 will not changesubstantially when the balloon is inflated or deflated.

In some embodiments, a single fiber 912 forms multiple spaced apartloops 914 extending continuously over the length of fiber reinforcementlayer 910. In this configuration, fiber 912 will extend continuously, ina generally longitudinal direction, between necks 908 of base balloon902, while changing directions with each loop. In this variation, fiber912 may extend continuously in a generally longitudinal direction overbase balloon 902 between necks 908 without passing around thecircumference of the base balloon. In one configuration, all of fibers912 may extend generally longitudinally along the length of base balloon902 between necks 908 with substantially no fibers extending completelyaround the circumference of base balloon 902 anywhere between necks 908.

In another variation, a single fiber 912 forms multiple spaced apartloops extending continuously around the circumference of fiberreinforcement layer 910. In this configuration, fiber 912 will extend agenerally circumferential direction around the circumference of baseballoon 902 while changing directions with each loop. In this variation,fiber 912 may extend continuously in a generally circumferentialdirection around base balloon 902 between necks 908 without extendinglongitudinally over the length of base balloon 902 between necks 908. Inone configuration, all of fibers 912 may extend generally continuouslyand circumferentially around the circumference of base balloon 902 withsubstantially no fibers extending longitudinally over the entire lengthof base balloon 902 between necks 908.

After placement on the balloon, each fiber 912 leading into, and out of,a loop 914 with other fibers will form an angle (denoted “L”) with alongitudinal axis 11-11 of the balloon. In some embodiments, the knitangle “L” may vary from location to location over the surface of theballoon to provide the best fit for the knitted layer. The knitted fiberlayer 910 is secured to the outer surface of the base balloon 902 usingan adhesive such as a polyurethane and/or overcoated with a materialsuch as Pebax®.

In other embodiments, as illustrated in FIG. 11, fibers 912 are disposedbetween an outer layer 920 and base balloon 902 with an adhesive layer922 securing the outer layer, fibers and base balloon together. As shownin FIG. 12, in yet other variations outer layer 920 may be fused to baseballoon 902 by means of solvent welding, heat, pressure or a combinationthereof with fibers 912 are disposed between outer layer 920 and baseballoon 902 such that the base balloon, fibers and outer layer aresecured together and affixed in position relative to each other.

In preferred embodiments, the knit angle “L” at each particular locationdoes not substantially change when the balloon goes from an uninflatedstate to an inflated state, or vice versa. Similarly, in the same orother preferred embodiments, the loop length “LD” does not substantiallychange when the balloon goes from an uninflated state to an inflatedstate, or vice versa. In other words, the spacing of loops 914 relativeto adjacent connected loops 914 and base balloon 902 does not changewhen the balloon is inflated.

It will be appreciated by those skilled in the art having the benefit ofthis disclosure that the disclosure provides a non-compliant medicalballoon having braided reinforcement and methods relating to thefabrication and/or use of same. It should be understood that thedrawings and detailed description herein are to be regarded in anillustrative rather than a restrictive manner, and are not intended tolimit the flowing claims to the particular forms and examples disclosed.On the contrary, further modifications, changes, rearrangements,substitutions, alternatives, design choices, and embodiments apparent tothose of ordinary skill in the art, without departing from the spiritand scope of the disclosure and following claims. Thus, it is intendedthat the following claims be interpreted to embrace all such furthermodifications, changes, rearrangements, substitutions, alternatives,design choices, and embodiments.

1. A medical balloon comprising: a balloon including a generallycylindrical section disposed between generally conical sections; and afabric layer comprising a plurality of braided fibers, wherein thebraided fibers have a fiber pitch and the fiber pitch around at leastone conical section is less than the fiber pitch at the cylindricalsection.
 2. The medical balloon of claim 1 wherein the balloon isnon-compliant.
 3. The medical balloon of claim 2 wherein when theballoon is internally pressurized substantially no change occurs in anangle formed between the fibers.
 4. The medical balloon of claim 3wherein the fabric layer is permanently affixed to the outer surface ofthe balloon.
 5. The medical balloon of claim 4 wherein the fabric layeris a braided fiber sleeve disposed around the balloon.
 6. The medicalballoon of claim 5 wherein the fabric layer comprises at least one seam.7. The medical balloon of claim 6 further including afiber-reinforcement layer.
 8. The medical balloon of claim 7 wherein thefiber-reinforcement layer includes longitudinal fibers.
 9. The medicalballoon of claim 8 wherein no single fiber extends completely over theballoon length.
 10. The medical balloon of claim 9 wherein the fiberscomprise inelastic material.
 11. The medical balloon of claim 10 whereina balloon wall has a thickness of 0.0005-0.002 inches.
 12. The medicalballoon of claim 7 wherein the fiber-reinforcement layer includescircumferential fibers.
 13. The medical balloon of claim 12 no singlefiber extends completely around the circumference of the balloon. 14.The medical balloon of claim 13 wherein the fibers comprise inelasticmaterial.
 15. The medical balloon of claim 14 wherein a balloon wall hasa thickness of 0.0005-0.002 inches.
 16. The medical balloon of claim 4further including a fiber-reinforcement layer.
 17. The medical balloonof claim 16 wherein the fiber-reinforcement layer includes longitudinalfibers.
 18. The medical balloon of claim 17 wherein no single fiberextends completely over the balloon length.
 19. The medical balloon ofclaim 16 wherein the fiber-reinforcement layer includes circumferentialfibers.
 20. The medical balloon of claim 19 no single fiber extendscompletely around the circumference of the balloon.